Does anyone have advice re treatment for chronic pain due to scar tissue caused by torn muscles?

In 2002 I tore muscles in my upper back, left side, between spine and left scapula. In 2004 I tore the same muscles on the right side. The injuries caused palpable ridges (vertical) on both side and chronic pain in the upper back and into the trapezoids and the sides of the neck. I have undegone trigger point injections, physical therapy (electical stim, ultrasound, massage), prolotherapy, botox injections, chiropractic (including Active Relese Therapy and Graston techniue), and accupuncture.  Some treatments have provided temporary relief, some provided no benefit whatsoever.  I received the most improvement from the Graston, which is the chiropractor using smooth stainless steel tools to rake over the ridges ("adhesions"). This breaks up the scar tissue.  The ridges have actually been reduced in size and the intensity of pain is now less, but the benefits seem to have reached a plateau. I also receive temporary relief by stretching the upper back muscles, particularly by doing pullups or using the upper back machines at th gym.

I also use muscle relaxants and narcotics once in a while. These provide only short term relief. I am looking for suggestions for other possible treatments to fully relieve this condition. I remember hearing about surgery to cut out the adhesions, but have not been able to find any info about this on line.